Process of inhibiting corrosion



United States Patent Ofilice 3,015,522 Patented Jan. 2, 1962 Ser. No. 860,339

18 Claims. (Cl. 252-855) AMIDINE PRODUCTS This application is a division of my application S.N. 721,643, filed March 17, 1958, now U.S. Patent No. 2,987,522.

This invention relates to compounds containing both a cyclic amidine ring and an alkylene ring containing a @N group in the ring (the latter ring hereafter referred to as the aza-alkylene ring), said rings being joined to each other through the 1-position of the cyclic amidine ring and the carbon atom of the aza-alkylene ring which is attached through a double bond to the nitrogen atom of the aza-alkylene ring (hereafter called the 2-position of the aza-alkylene rings), by means of a single valence bond or an (AX) radical, etc. where A is an alkylene radical and X comprises oxygen, amino or sulfur, and n is a whole number, for example 110 or higher, but preferably 1. This invention also relates to process of using, for example, these compounds as corrosion inhibitors. These compounds are exemplified by the following formulae:

(Cllzls and the above compounds containing 6 member cyclic amidine rings such as nlist;

THE CYCLIC AMIDINE PRECURSOR The expression cyclic amidine is employed in its usual sense to indicate ring compounds in which there are present either 5 or 6 members, and having 2 nitrogen atoms separated by a single carbon atom supplemented by either two additional carbon atoms or three additional carbon atoms in the main chain completing the ring. All the carbon atoms may be substituted. The nitrogen atom of the ring, involving two monovalent linkages (the 1-position), may be unsubstituted or substituted with a group containing at least one labile hydrogen capable of reacting with the aza-alkylene precursor, for example, an alkylene amine group, a polyalkylene amino group, an alkylene hydroxyl group, a polyoxyalkylene hydroxy group, an alkylenethiol group, a polythioalkylenethiol group, a polyalkylene group containing both sulfur and oxygen, nitrogen and oxygen, nitrogen, sulfur and oxygen, etc.

These cyclic amidines are further characterized as being substituted imidazolines and tetrahydropyrimidines in which the two-position carbon of the ring is generally bonded to a hydrocarbon radical or comparable radcal derived from an acid, such as a low molal fatty acid, a high molal fatty acid, or comparable acids, aromatic acids, polycarboxy acids, acids containing heterocyclic rings, and the like.

For details of the preparation of imidazolines from amines, see the following U.S. Patents, U.S. No. 1,999,- 989 dated April 30, 1935, Max Bockmuhl et al.; U.S. No. 2,155,877 dated April 25, 1939, Edmund Wa dmann et al.; and U.S. No. 2,155,878 dated April 25, 1939, Edmund Waldmann et a]. Also see Chem. Rev. 32, 47 (43), and Chem. Rev. 54, 593 (54).

Equally suitable for use in preparing compounds useful in my invention and for the preparation of tetrahydropyrimidines substituted in the 2-position are the corresponding poly-amines containing at least one primary amino group separated from the first primary amino group by three carbon atoms instead of being separated by only 2 carbons as with imidazolines. This reaction, as in the case of the imidazolines, is generally carried out by heating the reactants to a temperature at which 2 moles of water are evolved and ring closure is effected. For details of the preparation of tetrahydropyrimidines, see German Patent No. 700,371 dated December 18, 1940, to Edmund Waldmann and August Chwala; German Patent No. 701,322 dated January 14, 1941, to Karl Kiescher, Ernst Urech and Willi Klarer, and U.S.

Patent No. 2,194,419 dated March 19, 1940, to August Chwala.

Substituted imidazolines and tetrahydropyrimidines are obtained from a variety of acids beginning with the onecarbon acid (formic) through and including higher fatty acids or the equivalent having l30 carbon atoms such as from 8-22 carbons. Modified fatty acids also can be employed as, for example, phenyl stearic acid or the like. Cyclic acids may be employed, including naphthenic acids. A variety of other acids, including benzoic acid, substituted benzoic acid, salicyclic acid, and the like, have been employed to furnish the residue ll 11c from the acid RCOOH in which the C of the residue is part of the ring. The fatty acids employed, for example, may be saturated or unsaturated. They may be hydroxylated or nonhydroxylated. Branched long chain fatty acids may be employed. See J, Am. Chem, Soc. 74, 2523 (1952). This applies also to the lower molecular weight acids as well.

Among sources of such acids may be mentioned straight chain and branched chain, saturated and unsaturated, aliphatic cycloaliphatic, aromatic, hydroaromatic, aralkyl acids, etc.

Examples of saturated aliphatic monocarboxylic acids comprise: foamic, acetic, proprionic, butyric, valeric, caproic, heptanoic, caprylic, nonanoic, capric, undecanoic, lauric, tridecanoic, myriatic, pentadecanoic, palmitic, heptadecanoic, stearic, nonadecanoic, eicosanoic, hcneicosanoic, docosanoic, tricosanoic, tetracosanoic, pentacosanoic, cerotic, heptacosanoic, montanic, no-nacosanoic, melissic and the like.

Examples of ethylenic unsaturated aliphatic acids comprise: acrylic, methacrylic, crotonic, anglic, teglic, the pentenoic acids, the hexenoic acids, for example, hydrosorbic acid, the heptenoic acids, the octenoic acids, the nonenoic acids, the decenoic acids, for example, obtusilie acid, the undecenoic acids, the dodencenoic acids, for example, lauroleic, linderic, etc., the tridecenoic acids, the tetradecenoic acids, for example, myristoleic acid, the pentadecenoic acids, the hexadecenoic acids, for example, palmitoleic acid, the heptadecenoic acids, the octodecenoic acids, for example, petrosilenic acid, oleic acid, elaidic acid, the nonadecenoic acids, for example, the eicosenoic acids, the docosenoic acids, for example, erucic acid, brassidic acid, cetoleic acid, the tetracosenic acids, and the like.

Examples of dienoic acids comprise the pentadienoic acids, the hexadienoic acids, for example, sorbic acid, the octadienoic acids, for example, linoleic, and the like.

Examples of the trienoic acids comprise the octadecatrienoic acids, for example, linolenic acid, eleostearic acid, pseudo-eleostearic acid, and the like.

Carboxylic acids containing functional groups such as hydroxy groups can be employed. Hydroxy acids, particularly the alpha hydroxy acids comprise glycolic acid, lactic acid, the hydroxyvaleric acids, the hydroxy caproic acids, the hydroxyheptanoic acids, the hydroxy caprylic acids, the hydroxynonanoic acids, the hydroxycapric acids, the hydroxydecanoic acids, the hydroxy lauric acids, the hydroxy tridecanoic acids, the hydroxymyristic acids, the hydroxypentadecanoic acids, the hydroxypalmitic acids, the hydroxyhexadecanoic acids, the hydroxyhcptadecanoic acids, the hydroxy stcaric acids, the hydroxyoctadecenoic acids, for example, ricinoleic acid, ricinelaidic acid, hydroxyoctadecynoic acids, for example, ricinstearolic acid, the hydroxyeicosanoic acids, for example, hydroxyarachidic acid, the hydroxydocosanoic acids, for example, bydroxybehenic acid, and the like.

Examples of acetylated hydroxy acids comprise ricinoleyl lactic acid, acetyl ricinoleic acid, chloroacetyl ricinoleic acid, and the like.

Examples of the cyclic aliphatic carboxylic acids comprise those found in petroleum called naphthenic acids, hydnocarbic and chaumoogric acids, cyclopentane carboxylic acids, cyclohexanecarboxylic acid, campholic acid, fencholic acids, and the like.

Examples of aromatic monocarboxylic acids comprise benzoic acid, substituted benzoic acids, for example, the toluic acids, the xyleneoic acids, alkoxy benzoic acid, phenyl benzoic acid, naphthalene carboxylic acid, and the like.

Mixed higher fatty acids derived from animal or vegetable sources, for example, lard, cocoanut oil, rapeseed oil, sesame oil, palm kernel oil, palm oil, olive oil, corn oil, cottonseed oil, sardine oil, tallow, soyabean oil, peanut oil, castor oil, seal oils, whale oil, shark oil, and other fish oils, teaseed oil, partially or completely hydrogenated animal and vegetable oils are advantageously employed. Fatty and similar acids include those derived from various waxes, such as beeswax, spermaceti, montan wax, Japan wax, coccerin and carnauba wax. Such acids include carnaubic acid, cerotic acid, lacceric acid, montanic acid, psyllastearic acid, etc. One may also employ higher molecular weight carboxylic acids derived by oxidation and other methods, such as from paraffin wax, petroleum and similar hydrocarbons; resinic and hydroaromatic acids, such as hexahydrobenzoic acid, hydrogenated naphthoic, hydrogenated carboxy diphenyl, naphthenic, and abietic acid; aralkyl and aromatic acids, such as Twitchell fatty acids, naphthoic acid, carboxydiphenyl pyridine carboxylic acid, blown oils, blown oil fatty acids and the like.

Other suitable acids include phenylstearic acid, benzoyl nonylic acid, cetyloxybutyric acid, cetyloxyacetic acid, chlorstearic acid, etc.

Examples of the polycarboxylic acids comprise those of the aliphatic series, for example, oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, nonanedicarboxylic acid, decanedicarboxylic acids, undecanedicarboxylic acids. and the like.

Examples of unsaturated aliphatic polycarboxylic acids comprise fumaric, maleic, mesoconic, citraconic, glutonic, itaconic, muconic, acenitic acids, and the like.

Examples of aromatic polycarboxylic acids comprise phthalic, isophthalic acids, terephthalic acids, substituted derivatives thereof (e.g. alkyl, chloro, alkoxy, etc, derivatives), biphenyldicarboxylic acid, diphenylether dicarboxylic acids, diphenylsulfone dicarboxylic acids and the like.

Higher aromatic polycarboxylic acids containing more than two carboxylic groups comprise hemimellitic, trimellitic, trimesic, mellophanic, prehnitic, pyromellitic acids, mellitic acid, and the like.

Other polycarboxylic acids comprise the dimeric, trimeric and poly acids, for example, Emery Industries polymeric acids such as those described in US. Patent 2,763,- 612, and the like. Other polycarboxylic acids comprise those containing ether groups, for example, diglycollic acid. Mixtures of the above acids can be advantageously employed.

In addition, acid precursors such as esters, acid chlorides, glycerides, etc. can be employed in place of the free acid.

As is well known, cyclic amidines containing in the 1- position a group containing a labile hydrogen, capable of reacting with the aza-alkylene precursor, can be prepared by reacting a suitable amine with the desired carboxylic acid under cyclizing conditions, i.e., removal of 2 moles of water for each equivalent of carboxylate radical. Thus, where one employs a diamine such as ethylene or propylene diamine, a cyclic amidine which is unsubstituted in the 1-position is obtained. This compound can be reacted with such compounds as alkylene oxides, alkylene sulfides, alkylene imines and the like to produce compounds of the formula r N N-(AX)nH where Z is the alkylene residuum of the cyclic amidine ring, derived from the cyclic amidine forming polyamine, R is the group derived from the carboxylic acid, and A, X and n have the meaning stated above for this side chain.

Alternatively amino and polyarnino substituted cyclic amidine compounds can be prepared from polyamines such as a triamine or higher amines, for example, diethylene triamine, triethylene tetramine, tetraethylene penta- 1 mine, corresponding propylene analogues, etc. Thus, when one reacts diethylene triamine with a carboxylic acid, one obtains Hydroxy-substituted imidazolines and tetrahydropyrimidines can be obtained in the manner described above from a wide variety of polyamines containing hydroxy groups. Thus, where one starts with a polyamine, for example, a diamine of the following formula:

where Z and Z have a 2 or 3 carbon chain in the main chain, one obtains the hydroxyalkylene compounds useful in this invention. In addition, one can start with ethylene diamine or with 1,2-propylene diamine, 1,3- propylene diamine or other polyamines and then react the cyclic amidine so obtained with alkylene oxides so as to produce a terminal hydroxy group since the nitrogen bonded hydrogen on the 1-position on the ring reacts with alkylene oxides. In addition, the hydroxyalkylene group can be oxyalkylated.

Alkylene oxides comprise those of the general formula,

RCHCH2 where R is a hydrogen or an alkyl group. Among the alkylene oxides that may be employed are ethylene, propylene, butylene, octylene, etc. oxides. Other oxyalkylation agents such as glycide, epichlorohydrin, styrene oxide, etc., can be employed.

Thiol-containing compounds are prepared in a manner analogous to that employed in preparing the hydroxysubstituted cyclic amidines, for example, by employing by employing alkylene sulfides, by replacing the oxygen atoms of the hydroxy alkylene oxides, by employing sulfor replacing agents, etc.

Of course, it will be realized that the above compounds containing sulfur, oxygen or nitrogen can be employed as well as any combinations of two of these elements within the same molecule, for example, cyclic amidines prepared from Thus, cyclic amidines within the scope of this invention which are reacted with aza-alkylenes comprise compounds of the formulae:

and =CR(3= are the residues derived from the carboxylic acid, monocarboxylic acids in (l) and (3), and dicarboxylic acids in (2), where R comprises a hydrocarbon radical having, for example, 1-30 carbon atoms, hydrocarbons in which the carbon atom chain is interrupted by oxygen, etc.; and B is a hydrogen or a hydrocarbon radical; D is a radical, for example -(AX) where X is amino, oxygen or sulfur and A is an alkylene radical containing, for example, 23 carbons in its main chain wherein n is a whole number, for example, 1-10 or higher, but preferably 1, where H indicates the presence of labile hydrogens wherein m is a whole number equal to the replaceable hydrogens on the side chain, for example, 1-6, but preferably I 3; and (CB is, for example, a divalent radical of the formula:

CH2=CH2-,

l CH3 CH3 CH3 1 CH3 In (2) CB s and the l-substituted side chain may be the same or different.

Actually, substituted cyclic amidines can be obtained from a variety of polyamines, but only in the instance where one starts with a triamine or higher amine is there a residual group having a primary amino radical as herein required. This does not mean, however, that one could not start with ethylene diamine or with 1,2-propylene diamine. The cyclic amidines so obtained could be reacted with a mole of ethylene imine or propylene imine so as to introduce the terminal primary amino group. From a practical standpoint, however, the most readily available polyamines are ethylene diamine, diethylene triamine, triethylene tetramine, and tetraethylene pentamine. No particular advantage has been found in using other polyamines in which some other divalent radical, such as CH3 H For this reason examples in Table I are limited appears.

dily available polyto derivatives of the four most rea amines above indicated.

Table I Heuzoic: C reset mic Naphthenio lable on a large scale for the The only polyamines avai dines are propylene dimidazolines of Table I immediately following.

Table II Phonyl acetic. Polar-conic Laurie.

Steeric.

Ben zoic P-me tlioxy benz llytlroxy bntyrie. Netbyloctadccanoid .l. Nnphthenlc 2Tb-.. Palmiticinto the amine. Tetrahydropyed in the manufacture of suitable from dicarboxylic acids is comhen monocarboxylic acids are mines derived from the three The procedure employ substituted imidazolines parable to that employed w used as reactants. Suitable a In the use of dicarboxy acid, the bulk of the examples were obtained from 3,3'-iminobispropylamine. These compounds which appear in Table IV are comparable to those which appeared in Table III preceding.

Table IV 45 m m R'N N N-R o L-n 3 50 13x HOOC-ROOOH source of -oRo- R 1L... Alkenylsuccinlc .c CHQCH'JCHZNH! Suocinic CHzCHzCH NHz Glutaric CHzCHgCHzNH: Ample." ClIQOHQCIIiNIIQ SllbGl'i iL- OHaCHzCHgNl-Iz Sebacw.-. CIliCI'IEOHZNI'IQ Pimel CHQGHQGHQNHQ Aaelaic OHQC}I2CI'I2NII2 Nonodecane dicarboxylicflu CH20}12CH2NHI Eieosane dicarboxylic GIIZCI'IZCHQNH! Dl 21370011: CHzc H2O H QNH: Ethylene bisglyc0lic. CHzCI-IzCHzNHz Methylene disalicycllc CHQCHQCHQNH: Dllinoleie CHZCHQCHfiNIIQ Stearyl nialonic. CHQCI-IZGH NH Lauryl succinic CHQCHQCH N H Isotetradecyl suct'inlc. CH CH'ZGHQNHQ CHzCHgCIhNH; GHzCHzCHzNIlg CHuCH ClIgNH: CHQCIIQCH NHZ CIhCHgCHzNI-h In addition, one can employ hydroxy compounds as the amidine precursor, for example, cyclic amidines shown in the above tables wherein R is -(CH CH O) H where n is ll0, but preferably 1. Thus, R may be --CH CH OH, -(CH CH O) H, -(CH CH O) H, etc. In addition, the -CH -CH group may be a higher homologue, for example, -propylene, butylene, etc.

Furthermore, R can also be -(CH CH S) ,H where n is 1-10, but preferably 1, forming a compound analogous to the above oxygen compounds. Additionally, R can be a group containing (CHCH X),,H where X may be NH, -O, S, and all three, two, or one of these elements can be present in the R grouping, for example, where R is ontorn (.Il CH -OII -CII CH --S-CH CH OH -CH CH SCH CH OCH CH NH and the like.

THE AZA-ALKYLENE PRECURSOR The aza-alkylene precursors are O-organoalkylenc lactims and are in essence o-organo derivatives of enolic lactams, for example O-alkyl derivatives, e.g. the o-methyl, o-ethyl, etc. derivatives of alkylene lactams, such as lactams containing, for example, 5-8 member rings such as butyrolactam, valerolactam, caprolactam, heptylolactam. They may be described by the following formula:

where R is alkyl and R is hydrogen, alkyl, etc. or another radical containing groups that do not enter into or interfere with the reaction of the cyclic amidine with the azaalkylenes, 12:3-6.

Further discussion of the preparation of O-organoalkylcne lactims is unnecessary since their preparation is well known, having been described in Benson and Canns, J.A.C.S. 70, 211548 (1948), Schlack U.S. 2,356,622,

Knoll A-G French Patent 673,628, Schmidt and Zutavein, 3

German Patent 539,969, and elsewhere. The preferable class is the O-lower alkyl lactims, most preferably ethyl or methyl. The preferable species is the o-methyl 'ycaprolactim.

THE CYCLIC AMIDINE-LACTIM REACTION PRODUCT is reacted with O-methylcaprolactim the chief product is and a smaller amount of CHgCHaN C=N Where more than one equivalent of the lactim per labile cyclic amidine hydrogen is employed, an increased amount of the latter disubstituted compound is generally formed. In addition, shorter reaction times and lower temperature favor the monosubstituted products while higher temperatures and longer reaction times favor the disubstituted product.

In general, the reaction is carried out under such conditions under which the alcohol is distilled from the reaction mixture, and the measurement of the alcohol removed is an excellent method of judging reaction completion. A solvent or entraining agent may be employed, if desired. Although the temperature and time may vary widely depending on the particular reactants employed, one can advantageously employ temperatures of to 250 C., but preferably to 200 C. and times of 0.5 to 8 hours, but preferably 1 to 4. The reaction and prodnot produced can be summarized by the following equation:

alcohol removal N l I) cyclic amidine-lactim reaction product The meanings of the symbols designated in the above equation have the same meaning as stated above. The Zs, CR"s, and Ds may be the same or different. Thus one amidine ring may be a S-member ring and the other a 6-membered ring, one aza-alkylene may be a 6-membcr ring and the other a S-member ring, and one D may be CH CH O and the other CH CH N, etc.

Specific examples of the cyclic-amidine-lactim reaction product comprise the reaction products of (l) the cyclic amidines of Tables I-IV, their oxygen and sulfur analogues and (2) the O-methyl and O-ethyl butyro-, valero-, caproand heptylo-lactims.

EXAMPLES In general, the compounds of this invention are prepared by reacting the cyclic amidine with the O-methyl lactim at a temperature of ISO-200 C. for about l-4 hours or until no more alcohol is given off. The products are purified by distillation under reduced pressure.

11 12 E AM I In addition to the honiologues series of compounds shown in Table V, other compounds are similarly prepared in the manner shown in Example 1. Examples 1 of these compounds are shown in the following table.

One mole of N N-UmGHmm Table VI Formula 1 and one mole of 1mm N\ /N D C. N

(#:N C V ((1112):. It. are reacted at 160 Ill-185 C. in a flask attached to a Formula 2 Dean-Stark water trap until alcohol ceased distilling over N\ 7 (about 2 hours). The viscous product is then purified by Z E. A distillation at 215 C. at 0.25 mm. to yield a product l a} which is a viscous liquid which analyzed for 27.50% nitrogen (calculated 26.92%). The product is L L (:ZN (::,\I

H ((91121 ((Illin ngc/tv-cittoinN-o wigs). Formula 3 t .1 z, a H In addition, a small amount of the disubstituted product \NMD O A i i fiflin /.to1-1 G1I2N:[ one, R 11 Formula 4 is also formed. /N N\ In order to save repetition detail, the results of reactions carried out employing the homologues series imidazolines is presented in the following Table V. 1

C21[ NCg1'I;-- Table V 1, N

--c11 N 062%. i CH2 ii lf-(Il CIIgNII-C L \L,/ 2 Ex. Formula R Z D GHQ-om 5 2 Percent nitrogen Distillation of product 9 0 Ex. R 5 Pressure Tomperv 6 Calcd Found trnrn.) M313, (g:HggziR%i 2 ionbiNnII 5 .0 20.92 27.50 0. 25 215 5 2s. 23 24. 00 0. 27 245 23. 31 23. :15 0. 20 211 22. 40 22. 25 0.15 242 5 20. 1s 10. 25 0. 40 314 19. 17 151.03 0. as 240 13.30 18.25 0. 30 233 5 17.50 17.15 0.35 213 5 16.77 10.01 0. 27 25s (Cllrizfl 1'1-z 1s 5 15.47 15.59 0.30 218 (0111):" mums"-.. 5 11. 6t; 14. 53 0. 00 210 13. 40 13. 15 0. 95 3505 Cflnabm USE AS CORROSION INHIBITOR More specifically, this phase of the invention relates to Th5 Products gi wlthha F g the inhibition of corrosion in the petroleum industry with the prof'lucts to sohdlfy mg as t 8 Size 0 t a specific reference to producing wells, pipe lines, refineries, group increases. In addition, lesser amounts of the d1- tank Stmage, etc. subsmuted Products The use of a corrosion inhibiting agent in the oil industry and other industries, and particularly for the protection of ferrous metals, is well known. For example, N 1 CII CHQN= o N see US. Patents Nos. 2,736,658 dated February 28, 1954, *c l to Pfohl et a1., and 2,756,211 dated July 24, 1956, to Jones, and 2,727,003 dated December 13, 1955, to Hughes. More specifically then, and particularly from the standare also formed. In general, shorter reaction time and point of oil production, this aspect of the invention relower temperature favor the monosubstituted products lates t0 lnhlbltlng corrosion caused by hydrogen sulfide, while higher temperatures and longer reaction time favor carbon dioxide, inorganic acids, organic acids, combinathe disubstituted compounds. tions of each with oxygen, and with each other and oxygen. More particularly, it relates to treating wells to mitigate metal corrosion and associated difficulties.

It should also be pointed out that the corrosiveness of oil well brines will vary from well to well, and the proportion of corrosion inhibiting agent added to the well fluids should also be varied from well to well. Thus, in some wells it may be possible to efiectively control corrosion by the addition of as little as p.p.m. of my new compositions to the well fluids, whereas in other wells, it may be necessary to add 200 ppm. or more.

In using my improved compositions for protecting oil Well tubing, casing and other equipment which comes in contact with the corrosive oil-brine production, I find that excellent results are obtained by injecting an appropriate quantity of a selected composition into a producing well so that it mingles with the oil-brine mixture and comes into contact with the casing, tubing, pumps and other producing equipment. I may, for example, introduce the inhibiting composition into the top of the casing, thus causing it to flow down into the well and thence back through the tubing, etc. In general, I have found that this procedure suflices to inhibit corrosion throughout the entire system of production, and collection, even including field tankage.

In case serious emulsion or gel problems are encountered, demulsifiers are advantageously added. This is important not only to avoid the troublesome emulsions and gels themselves, but also to improve corrosion inhibition. The explanation of less effective corrosion inhibition in the presence of emulsions apparently is that the inhibitor is somewhat surface-active. That is, it is concentrated at interfacial surfaces. Since this surface is great in an emulsion, most of the inhibitor will be concentrated in these interfaces and little will remain in the body of the oil for deposition on the metal surfaces. In many wells, oil-in-water type emulsions often occur naturally. In such wells the inhibitors herein described tending to form water-in-oil type emulsions, often decrease the emulsion problems naturally present. Thus, in addition to being effective corrosion inhibitors, the herein described products tend to eliminate emulsion problems which sometimes appear when some of the present day inhibitors are used in oil wells or refinery processing.

The method of carrying out our process is relatively simple in principle. The corrosion preventive reagent is dissolved in the liquid corrosive medium in small amounts and is thus kept in contact with the metal surface to be protected. Alternatively, the corrosion inhibitor may be applied first to the metal surface, either as is, or as a solution in some carrier liquid or paste. Continuous application, as in the corrosive solution, is the preferred method, however.

The present process finds particular utility in the protection of metal equipment of oil and gas wells, especially those containing or producing an acidic constituent such as H 8, CO inorganic, organic acids, 0 and the like. For the protection of such wells, the reagent, either undiluted or dissolved in a suitable solvent, is fed down the annulus of the well between the casing and producing tubing where it becomes commingled with the fluid in the well and is pumped or flowed from the well with these fluids, thus contacting the inner wall of the casing, the outer and inner wall of tubing, and the inner surface of all well-head fittings, connections and flow lines handling the corrosive fluid.

Where the inhibitor composition is a liquid, it is conventionally fed into the well annulus by means of a motor driven injector pump, or it may be dumped periodically (e.g., once every day or two) into the annulus by means of a so-called boll weevil device or similar arrangement. Where the inhibitor is a solid, it is dropped into the well as a solid lump or stick, blown in as a powder with gas, or it may be Washed in with a small stream of the well fluids or other liquid. Where there is gas pressure on the casing, it is necessary, of course, to employ any of these treating methods through a pressure equalizing chamber equipped to allow introduction of reagent into the chamber, equalization of pressure between chamber and casing, and travel of reagent from chamber to well casing.

Occasionally, oil and gas wells are completed in such a manner that there is no opening between the annulus and the bottom of the tubing or pump. This results, for example, when the tubing is surrounded at some point by a packing held by the casing or earth formation below the casing. In such wells the reagent may be introduced into the tubing through a pressure equalizing vessel, after stopping the flow of fluids. After being so treated, the well should be left closed in for a period of time sufficient to permit the reagent to drop to the bottom of the well.

For injection into the well annulus, the corrosion inhibitor is usually employed as a solution in a suitable solvent, such as mineral oil, methylethyl ketone, xylene, kerosine, or even water. The selection of solvent will depend much upon the exact reagent being used and its solubility characteristics. It is also generally desirable to employ a solvent which will yield a solution of low freezing point, so as to obviate the necessity of heating the solution and injection equipment during winter use.

For treating wells with packed-off tubing, the use of solid sticks or plugs of inhibitor is especially convenient. These are prepared by blending the inhibitor with a mineral wax, asphalt or resin in a proportion sufficient to give a moderately hard and high-melting solid which can be handled and fed into the well conveniently.

The amount of corrosion preventive agent required in our process varies with the corrosiveness of the system, but where a continuous or semi-continuous treating procedure is carried out as described above, the addition of reagent in the proportion of from 5 parts per million to parts per million or more parts of corrosive fluid will generally provide protection.

These corrosion inhibitors can be used in combination with other wellknown corrosion inhibitors, for example, the cyclic amidine structures, the amido cyclic amidine structures, and the amino cyclic amidine structures, as disclosed in the Blair and Gross Reissue Patent No. 23,227. When the herein described products are mixed with corrosion inhibitors of the conventional type in the ratio of one-to-three, one-to-one, three-to-one, or the like, in numerous instances the effectiveness of the corrosion inhibitor thus obtained is often significantly greater than the use of either one alone.

Since these products are basic they can be combined with various acids to produce salts in which oil solubility is increased or decreased. Likewise, water solubility is increased or decreased. For instance, the products are mixed with one or more moles of an acid, such as higher fatty acids, dimerized fatty acids, naphthenic acids, acids obtained by the oxidation of hydrocarbons, as well as sulfonic acids such as dodecylbenzene sulfonic acid, petroleum mahogany acids, petroleum green acids, etc.

What has been said in regard to the acids which increase oil solubility and decrease water solubility applies with equal force and effect to acids of the type, such as acetic acid, hydroXy-acetic acid, gluconic acid, etc., all of which obviously introduce hydrophile character when they form salts or complexes, if complexes are formed. In addition. any of the acids described above in preparing the cyclic amidines are useful in preparing these salts.

As pointed out previously, the addition of corrosion inhibitors, particularly in the form of a solution by means of a metering pump or the like, is common practice. The particular corrosion inhibitors herein described are applied in the same manner as other corrosion inhibitors intended for use for the same purpose. For sake of brevity, as to the use of the corrosion inhibitor may be mentioned its solution and use in a suitable solvent such as mineral oil, methyl ethyl ketone, xylene, kerosene, high boiling aromatic solvent, or even water.

The following examples are presented to illustrate the superiority of the instant compounds as corrosion inhibitors.

STATIC WEIGHT LOSS TESTS These tests can be run on both synthetic and naturally occurring fluids. The test procedure involves the measure ment of the corrosive action of the fluids inhibited by the compositions herein described upon sandblasted S.A.E. 1020 steel coupons measuring '78 x 3% inches under conditions approximating those found in an actual producing well, and the comparison thereof with results obtained by subjecting identical test coupons to the corrosive action of identical fluids containing no inhibitor.

In the present test clean pint bottles are charged with 200 ml. of 10% sodium chloride solution saturated with hydrogen sulfate and 200 ml. of mineral spirits. The solution is adjusted to pH 6.5 with acetic acid and a redox of -360 by means of ammonium sulfide. A predetermined amount of inhibitor is then added. In all cases the inhibitor concentration is based on the total volume of fluid. Weighed coupons are then added, the bottles tightly sealed and allowed to remain at room temperature for 5 days. The coupons are then removed, cleaned by immersion in inhibited hydrochloric acid, dried and weighed.

The changes in the weight of the coupons during the corrosion tests are taken as a measurement of the effectiveness of the inhibitor compositions. Protection percentage is calculated for each test coupon taken from the inhibited fluids in accordance with the following formula X 100 percent protection N NCHC H N GsN l Hah R Test R Av. wt. Percent loss tmg.) protection OTHER USES These products are effective not only as corrosion inhibitors but can be used for a number of other purposes. For instance, they can be used as asphalt additives to increase the adhesiveness of the asphalt to the mineral aggregates. In the form of water soluble salts, for example, the acetate, hydroxyacetate, lactate, gluconate, phthalate, etc., they are useful as bactericides in the secondary recovery of oil. They can be subjected to extensive oxyalkylation by means of ethylene oxide, propylene oxide, butylene oxide, octylene oxide, or the like. These can be oxyalkylated and still have oil solubility as, for example, by the addition of propylene oxide or butylene oxide. or are oxyalkylated to produce water solubility as, for example, by means of ethylene oxide or glycide. They are also oxyalkylated by combinations of propylene oxide and ethylene oxide so that both water solubility and oil solubility remain. Thereupon they may, if desired, be acylated. Such products are useful for a variety of purposes and particularly for those where nonionic surfactants or sequestered cationic surfactants are indicated.

These compounds and their derivatives unexpectedly have a broad spectrum of uses and can be used, for example, as demulsifiers for oil-in-water emulsions; as corrosion inhibitors; as fuel oil additives for gasoline, diesel fuel, jet fuel, and the like; as lubricating oil additives, as scale preventatives; as chelating agents or to form chelates which are themselves useful, for example, anti-oxidants, fungicides, etc; as flotation agents, for example, as flotation collection agents; as asphalt additives or antistripping agents for asphalt-mineral aggregate compositions; as additives for compositions useful in acidizing calcareous stratas of oil wells; as additives for treating water used in the secondary recovery of oil and in disposal wells; as additives used in treating oil-Well strata in primary oil recovery to enhance the flow of oil; as emulsifiers for both oil-in-wztter and watcr-in-oil emulsions; as additives for slushing oils; as additives for cutting oils; as additives for oil to prevent emulsification during transport; as additives for drilling muds; as agents useful in removing mud sheaths from newly drilled wells; as dehazing or fog-inhibiting agents for fuels; as additives for preparing sand or mineral slurries useful in treating oil wells to enhance the recovery of oil; as agents for producing polymeric emulsions useful in preparing water-vapor impermeable paper board; as agents in paraflln solvents; as agents in preparing thickened silica uerogel lubricants; as gasoline anti-oxidant additives; as deicing agents for fuels; as antiseptic, preservative, bactericidal, bacteriostatic, germicidal, fungicidal agents; as agents for the textile industry, for example, as mercerizing assistants, as wetting agents, as rewetting agents, as dispersing agents, as detergents, as penetrating agents, as softening agents; as dyeing assistants, as anti-static agents, and the like; as additives for rubber latices; as an entraining agent for concrete and cements; as antistatic agents for rugs, floors, upholstery, plastic and wax polishes, textiles, etc., as detergents useful in metal cleaners, in floor oils, in dry cleaning, in general cleaning, and the like; as agents useful in leather processes such as in flat liquoring, pickling, acid degreasing, dye fixing, and the like; as agents in metal pickling; as additives in paints for improved adhesion of primers, in preventing water-spotting in lacquer; as anti-Skinners, for pigment flushing, grinding and dispersing; as anti-feathering agents in ink; as agents in the preparation of pulp and pulp slurries; as emulsifiers for insecticidal compositions and agricultural sprays such as DDT, 24D (Toxaphene), chlordan, nicotine sulfate, hexachloracyclohexane, and the like; as agents useful in building materials, for example, in the water repellant treatment of plaster, concrete. cement, roofing materials, floor sealers; as additives in bonding agents for various insulating building materials; and the like.

I claim:

1. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said metals with a compound of the formula:

where Z is selected from the group consisting of (l) 17 (CB;) and B is selected from the group consisting of hydrogen, and a lower alkyl group, and (2) A is a lower alkylene group; X is selected from the group consisting of O, S, NH and R is a hydrocarbon group having l-36 carbon atoms.

2. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said metals with a compound of the formula:

where A is a lower alkylenc radical, and R is a hydrocarbon group having l-36 carbon atoms.

A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said metals with a compound of the formula:

where R is a hydrocarbon group having 1-36 carbon atoms and A is the lower alkylene group.

4. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said metals with a compound of the formula:

where R is a hydrocarbon group having 1-36 carbon atoms.

5. A method of inhibiting corrosion of ferrous metals 50 in hydrocarbon systems characterized by contacting said metals with a compound of the formula:

where R is a hydrocarbon group having 1-36 carbon atoms.

6. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said 65 metals with a compound of the formula:

where R is a hydrocarbon group having l-36 carbon atoms.

7. A method of inhibiting corrosion of ferrous metals 7 18 in hydrocarbon systems characterized by contacting said metals with a compound of the formula:

where R is a hydrocarbon group having l-36 carbon atoms.

8. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said metals with a compound of the formula:

i (0 Hi) :-e R

where R is a hydrocarbon group having 1-36 carbon atoms.

9. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said metals with a compound of the formula:

Ill-( Q 2-37 where R is a hydrocarbon having 1-36 carbon atoms.

11. A method of inhibiting corrosion of ferrous metals 45 in hydrocarbon systems characterized by contacting said metals with a compound of the formula:

where R is a hydrocarbon group having 1-36 carbon atoms.

12. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said metals with a compound of the formula:

where R is a hydrocarbon group having 1-36 carbon atoms.

13. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said metals with where R is a hydrocarbon radical having i-30 carbon atoms.

14. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said metals with where R is a hydrocarbon radical having 1-30 carbon atoms.

15. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said metals with where R is a hydrocarbon radical having 130 carbon atoms.

16. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said metals with where R is a hydrocarbon radical having 13() carbon atoms.

18. A method of inhibiting corrosion of ferrous metals in hydrocarbon systems characterized by contacting said where R is a hydrocarbon radical having 1-30 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 2,468,163 Blair et a1 Apr. 26, 1949 2,792,390 Stromberg May 14, 1957 2,987,522 Shen June 6, 1961 

1. A METHOD OF INHIBITING CORROSION OF FERROUS METALS IN HYDROCARBON SYSTEMS CHARACTERIZED BY CONTACTING SAID METALS WITH A COMPOUND OF THE FORMULA 